Inorganic peroxygen compounds, particularly hydrogen peroxide and solid peroxygen compounds that dissolve in water and release hydrogen peroxide, such as sodium perborate and sodium carbonate perhydrate, have long been used as oxidizing agents for disinfection and bleaching purposes. The oxidizing action of these substances in dilute solutions is strongly dependent on the temperature; thus, for example, a sufficiently rapid bleaching of soiled fabrics by H2O2 or perborate in alkaline bleaching liquor is only achieved at temperatures above about 80° C. The oxidizing action of the inorganic peroxygen compounds at lower temperatures can be improved by the addition of bleach activators that are capable of yielding peroxycarboxylic acids under the given perhydrolysis conditions, and the numerous proposals known from the literature, principally from the classes of materials of the N- or O-acyl compounds, for example reactive esters, polyacylated alkylenediamines, particularly N,N,N′,N′-tetraacetylethylenediamine (TAED), acylated glycolurils, particularly tetraacetylglycoluril, N-acylated hydantoins, hydrazides, triazoles, hydrotriazines, urazoles, diketopiperazines, sulfurylamides and cyanurates, also carboxylic acid anhydrides, particularly phthalic anhydride, carboxylic acid esters, particularly sodium nonanoyloxybenzene sulfonate (NOBS), sodium isononanoyloxybenzene sulfonate, O-acylated sugar derivatives, such as pentaacetylglucose, and N-acylated lactams, such as N-benzoyl caprolactam. The bleaching action of aqueous peroxide wash liquors can be increased so much by the addition of these substances that already at temperatures of about 60° C. there is essentially the same activity as for the peroxide wash liquor alone at 95° C.
Using a differentiating approach, it was observed, however, that under fabric washing conditions, such bleach activators that release relatively short chain peroxycarboxylic acids (the most important example of this is TAED) exhibit a particularly pronounced efficiency against hydrophilic colored stains, whereas bleach activators that release relatively longer chain peroxycarboxylic acids (an example of this is NOBS) possess a higher efficiency against hydrophobic colored stains. Largely to achieve on average a high bleaching performance for all possible stains, the addition of mixtures of bleach activators that release percarboxylic acids with different chain lengths has been proposed on various occasions.
In attempts for energy-saving washing and bleaching processes, washing temperatures significantly below 60° C., particularly below 45° C., down to cold water temperature have also grown in importance over the last few years.
In general, the activity of the activator compounds known up to now noticeably decreases at these low temperatures. Therefore, there has been no lack of effort to develop more active activators for this temperature range. However, in specific cases one has to note that a highly active low-temperature bleach activator loses its efficiency at medium or high temperatures, in that higher demands on the cleaning performance of the washing or cleaning agent can similarly require an increased bleaching performance than that of the pure oxidizing agent.
On various occasions, the addition of transition metal compounds, particularly transition metal complexes, has also been proposed to increase the oxidizing strength of peroxygen compounds or also of atmospheric oxygen in washing and cleaning agents. Exemplary transition metal compounds that have been proposed for this purpose include salen complexes of manganese, iron, cobalt, ruthenium or molybdenum, carbonyl complexes of manganese, iron, cobalt, ruthenium or molybdenum, complexes of manganese, iron, cobalt, ruthenium, molybdenum, titanium, vanadium and copper with nitrogen-containing tripod ligands, and manganese complexes with polyazacycloalkane ligands, such as TACN.
It has now been surprisingly found that certain complexes, namely those with a ligand of the imino diol type, as described below, exhibit an excellent bleach-boosting action and boost the cleaning power of washing and cleaning agents, particularly against bleachable, but also against protein-containing stains, without the occurrence of damage to the thus treated fabric from the addition of the agent or from the combined addition of its previously cited components, wherein the bleaching action and cleaning power exceed those obtained by adding customary agents. Protein-containing stains are normally not oxidatively removable from fabrics.
Accordingly, a subject matter of the invention is the use of a bleach catalyst in the form of a complex of Fe, Mo, Mn and/or W, particularly Fe and/or Mn, with a ligand containing a structure of the Formula (I),
for boosting the cleaning power of washing and cleaning agents, particularly against bleachable and/or protein-containing stains, wherein the structure of the Formula (I) can also be bridged as well as mono or polysubstituted. Generally, the metal-ligand complex can be produced in a facile manner by mixing a metal salt of the corresponding metal with the corresponding ligand in an aqueous medium. The desired oxidation state can be favorably influenced by adjusting the redox potential to a suitable level.
Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.